Rotary couplings

ABSTRACT

A rotary shaft coupling of the so called Oldham coupling type including a flat metal coupling disc with grooves or slots on two perpendicular transverse axes to engage respectively with teeth or dogs attached to drive discs or flanges attached to the two drive shafts. Two surfaces of the slots or grooves on the coupling disc lie in a common transverse plane to avoid tilting moments on the disc and the disc is formed by a simple punching or stamping operation.

United States Patent [191 Smith [451 Feb. 5, 1974 ROTARY COUPLINGS [75]Inventor: John Cambridge Smith,

Cheltenham, England [73] Assignee: Hydro-Mite Limited, Cheltenham,

England [22] Filed: Oct. 6, 1971 [21] Appl. No.: 187,123

52 U.S.C1. 64/31, 64/16 [51] Int. Cl. Fl6d 3/04 [58] Field of Search64/31, 16

[5 6] References Cited UNITED STATES PATENTS 3,338,585 8/1967 Poorman64/31 1,488,497 4/1924 Higgins 2,220,799 11/1940 Edwards 64/31 9/ 1920Grundy 64/31 12/1947 Smith ..64/31 Primary ExaminerManuel A. AntonakasAssistant Examiner-Randall Heald Attorney, Agent, or Firm-William D.Hall et a1.

[ 5 7] ABSTRACT A rotary shaft coupling of the so called Oldham couplingtype including a flat metal coupling disc with grooves or slots on twoperpendicular transverse axes to engage respectively with teeth or dogsattached to drive discs or flanges attached to the two drive shafts. Twosurfaces of the slots or grooves on the coupling disc lie in a commontransverse plane to avoid tilting moments on the disc and the disc isformed by a simple punching or stamping operation.

3 Claims, 7 Drawing Figures ROTARY COUPLINGS This invention relates toso-called Oldham couplings in which a coupling element is interposedbetween two rotary drive members, the element having a connection witheach drive member which will permit relative sliding movement on atransverse axis, i.e., transverse to the rotary axis of the drivemember, the two transverse axes being approximately perpendicular. Suchcouplings will accommodate limited misalignment between the axes of thedrive members. It is an object of the present invention to provide animproved Oldham coupling which will be simple and economical tomanufacture and assemble, stable in operation, and capable oftransmitting comparatively large torsional loads within specific sizelimitations.

In conventional Oldham couplings the coupling element has ribs formed onopposite faces extending diametrically across the disc and angularlydisplaced at 90".. A coupling of this type has certain disadvantagesowing to the fact that the abutment surfaces on the two ribs aredisplaced axially so that a certain tilting moment is applied and thecoupling can become unstable. Furthermore although the design of thecoupling element is simple its production can be relatively expensiveinvolving removal of considerable amounts of metal by machiningoperations.

According to the present invention there is provided a rotary shaftcoupling assembly comprising a first drive flange secured to a firstshaft, and formed integral with a diametral drive rib on the face ofsaid flange remote from said shaft, said rib being of uniform solidrectangular cross-section, a second drive flange secured to a secondshaft approximately coaxial with said first shaft, said second driveflange having a pair of spaced drive lugs integral with said flange andextend ing from the face of said second flange remote from said secondshaft, said two drive lugs being approximately square as seen along thedirection of the axis of said second shaft, and positioned in line on acommon diameter of said flange, and of uniform solid rectangular crosssection as viewed along said diameter, and an intermediate couplingmember in the form ofa circular flat metal plate which constitutes thesole connection between said first and second drive flanges and has onedouble-ended diametral slot with closed ends, of a length greater thanthe length of said diametral drive rib, and two separate spaced radiallyextending singleended slots on a diameter perpendicular to saiddiametral slot, the inner ends of said single-ended radial slots beingcloser to the central axis of said intermediate coupling member than theouter ends of said doubleended slot, said diametral and radial slotsbeing dimensioned to receive and accommodate said drive rib and drivelugs respectively on said first and second drive flanges, and to permitlimited sliding movement thereof on two transverse mutuallyperpendicular axes, said diametral and radial slots having lateral flanksurfaces lying entirely within the common radial plane of saidintermediate coupling member, and said coupling member being formed .asa punched plate.

The invention may be performed in various ways and some specificembodiments will now be described by way of example, with reference tothe accompanying drawings: in which FIG. 1 is a side view of the end ofa first drive member to be coupled to another by an Oldham couplingaccording to the invention,

FIG. 2 is an end view of the member of FIG. 1,

FIG. 3 is a side view of a second drive member to be coupled to thefirst drive member,

FIG. 4 is an end view of the member of FIG. 3,

FIG. 5 is a radial section of the Oldham coupling, equivalent to theline V-V of FIG. 3,

FIG. 6 is a radial section of another form of Oldham coupling accordingto the invention, being a section on the line VIVI of FIG. 7, and

FIG. 7 is a side view of the coupling of FIG. 6.

The Oldham-type couplings to be described are for connecting two drivemembers or shafts on approximately parallel aligned axes. Each couplingwill however accommodate limited linear and angular misalignment betweenthe shafts while rotating and transmitting torque. The coupling may beincorporated into the rotary drive ofa machine such as a rotaryhydraulic pump or motor.

Referring to FIGS. 1 to 5, the end ofa first shaft (not shown) has acircular drive flange l, the end face of which has a concentric shallowannular formation 2 with two diametrically opposed lugs 3 ofapproximately square cross-section, which constitute means forconnection to an intermediate coupling element 4 (FIG. 5). A secondshaft 5 (FIG. 3) also has a circular drive flange 6 the end face ofwhich has a transverse diametral rib 7 of approximately squarecross-section, forming means for connection to the coupling element 4.The transverse rib 7 is shorter than the internal diameter of theformation 2, which is the same as the distance between the two lugs 3.

The intermediate coupling element 4 is a simple flat circular metal dischaving a slot 8 extending diametrically on a first transverse axisacross the centre of the disc but terminating short of the periphery ateach end. This slot is dimensioned to receive the diametral rib 7 on thedrive flange 6 and its length is such that a limited degree of endwisesliding movement can be obtained on this first transverse axis.

The coupling disc 4 also has a pair of aligned slots 9 extendingradially inwards from diametrically opposite points on the periphery, ona second transverse axis perpendicular to the first transverse axis. Thepositions and dimensions of these peripheral slots 9 are such that theywill engage the two spaced lugs 3 on the drive flange 1 and again permitlimited relative sliding movement on this second transverse axis.

The intermediate coupling disc 4 is located between the two driveflanges l and 6, which are held apart axially by bearings (not shown) sothat the coupling disc .is at all times free to move transversely andcompensate for misalignment of the shafts. There is no structure otherthan the disc interconnecting the drive flanges 1 and 6, and no otherstructure locating the disc 4, which is therefore free floating to movetransversely on the two mutually perpendicular axes while the couplingis rotating and torque is being transmitted.

It will be noted that the abutment surfaces formed by the flanks oredges of the slots 8 and 9 are in a common plane so that tilting momentsare eliminated or minimised. 'The coupling disc is simply stamped orpunched in one operation from a suitable sheet metal blank and is thusinexpensive to manufacture and provides for the transmission ofconsiderable torques.

A number of modifications are possible. For example in FIGS. 6 and 7 theintermediate coupling disc 4a is formed with two intersecting slotsproviding a cross" 10. In other respects this embodiment is similar tothat described above.

I claim:

1. A rotary shaft coupling assembly comprising a first drive flangesecured to a first shaft, and formed integral with a diametral drive ribon the face of said flange remote from said shaft, said rib being ofuniform solid rectangular cross-section, a second drive flange securedto a second shaft approximately coaxial with said first shaft, saidsecond drive flange having a pair of spaced drive lugs integral withsaid flange and extending from the face of said second flange remotefrom said second shaft, said two drive lugs being approximately squareas seen along the direction of the axis of said second shaft, andpositioned in line on a common diameter of said flange, and of uniformsolid rectangular cross-section as viewed along said diameter, and anintermediate coupling member in the form ofa floating circular flatmetal plate which constitutes the sole connection between said first andsecond drive flanges and has one double-ended diametral slot with closedends, of a length greater than the length of said diametral drive rib,and two separate spaced radially extending single-ended slots on adiameter perpendicular to said diametral slot, the inner ends of saidsingle-ended radial slots being closer to the central axis of saidintermediate coupling member than the outer ends of said double-endedslot, said diametral and radial slots being dimensioned to receive andaccommodate said drive rib and drive lugs respectively on said first andsecond drive flanges, and to permit limited sliding movement thereof ontwo transverse mutually perpendicular axes while said coupling assemblyis rotating and torque is being transmitted between said drive flanges,said diametral and radial slots having lateral flank surfaces lyingentirely within the common radial plane of said intermediate couplingmember, and said coupling member being formed as a punched plate.

2. A shaft coupling according to claim 1, wherein said two single-endedslots in said intermediate coupling member open into the externalperiphery of said member.

3. A shaft coupling according to claim 1, wherein said two single-endedslots in said intermediate coupling member open into said diametral slottherein,

forming a cross-shaped aperture.

1. A rotary shaft coupling assembly comprising a first drive flangesecured to a first shaft, and formed integral with a diametral drive ribon the face of said flange remote from said shaft, said rib being ofuniform solid rectangular cross-section, a second drive flange securedto a second shaft approximately coaxial with said first shaft, saidsecond drive flange having a pair of spaced drive lugs integral withsaid flange and extending from the face of said second flange remotefrom said second shaft, said two drive lugs being approximately squareas seen along the direction of the axis of said second shaft, andpositioned in line on a common diameter of said flange, and of uniformsolid rectangular cross-section as viewed along said diameter, and anintermediate coupling member in the form of a floating circular flatmetal plate which constitutes the sole connection between said first andsecond drive flanges and has one double-ended diametral slot with closedends, of a length greater than the length of said diametral drive rib,and two separate spaced radially extending single-ended slots on adiameter perpendicular to said diametral slot, the inner ends of saidsingle-ended radial slots being closer to the central axis of saidintermediate coupling member than the outer ends of said double-endedslot, said diametral and radial slots being dimensioned to receive andaccommodate said drive rib and drive lugs respectively on said first andsecond drive flanges, and to permit limited sliding movement thereof ontwo transverse mutually perpendicular axes while said coupling assemblyis rotating and torque is being transmitted between said drive flanges,said diametral and radial slots having lateral flank surfaces lyingentirely within the common radial plane of said intermediate couplingmember, and said coupling member being formed as a punched plate.
 2. Ashaft coupling according to claim 1, wherein said two single-ended slotsin said intermediate coupling member open into the external periphery ofsaid member.
 3. A shaft coupling according to claim 1, wherein said twosingle-ended slots in said intermediate coupling member open into saiddiametral slot therein, forming a cross-shaped aperture.